A Silicon Valley start-up called Unity Semiconductor has developed new memory technology, on the strength of which it has disclosed its objective to have the smallest die size and the lowest manufacturing cost per bit in the industry. There appears to be some substance behind these lofty goals, given that the company recently obtained $22 million in funding.
The storage class non-volatile memory (NVM) products company has achieved encouraging results using innovative, multilayer, memory array architectures and a new breakthrough technology called CMOx, which is based on the use of new materials called conductive metal oxides into the semiconductor process that reportedly allows for ionic motion.
Founded in 2002, Unity claims to have successfully created the world’s first passive rewritable cross-point memory array that requires no transistors in a memory cell. The company has been processing 64 kilobit products for two years, 64 megabit products for one year, and is in design of a 64 gigabit product that is now close to tape-out and slated for pilot production in the second half of 2010, with volume production in the second quarter of 2011.
According to Unity, as the first cross-point storage device, CMOx is capable of being scaled below 20 nanometres with a volumetric density better than 4 bits per cell NAND. It allegedly uses less than 1 microamp of write current per cell, has a 10x write performance and better endurance compared to NAND, and at a much lower cost.
The memory effect of CMOx technology is based upon the atomic-scale movement of ionic charge carriers. CMOx can be utilised to form a passive cross-point multilayer memory array, as it does not require a transistor per cell. Other memory technologies, such as phase-change memory (PCM) and magneto-resistive random access memory (MRAM), use a transistor per cell and are not amenable to the cross-point multilayer chip architecture.
Unity’s multilayer cross-point array utilises a resistance change element, although it is not a resistive RAM memory cell such as is being developed by a few other companies. Rather, in the CMOx technology, conduction is uniform across the device instead of being filamentary, allowing for more reliable and predictable scaling to future process nodes. The passive nature of the cross-point memory array architecture contributes to what are said to be the densest memory devices of all the next-generation NVM technologies. Further, it enables the physical stacking of multiple layers of memory; Unity’s CMOx-based designs use four physical layers of multilevel cell (MLC) memory.
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